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ruby--ruby/include/ruby/3/constant_p.h
2020-04-08 13:28:13 +09:00

37 lines
1.8 KiB
C++

/** \noop-*-C++-*-vi:ft=cpp
* @file
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
* @warning Symbols prefixed with either `RUBY3` or `ruby3` are
* implementation details. Don't take them as canon. They could
* rapidly appear then vanish. The name (path) of this header file
* is also an implementation detail. Do not expect it to persist
* at the place it is now. Developers are free to move it anywhere
* anytime at will.
* @note To ruby-core: remember that this header can be possibly
* recursively included from extension libraries written in C++.
* Do not expect for instance `__VA_ARGS__` is always available.
* We assume C99 for ruby itself but we don't assume languages of
* extension libraries. They could be written in C++98.
* @brief Defines #RUBY3_CONSTANT_P.
*
* Note that __builtin_constant_p can be applicable inside of inline functions,
* according to GCC manual. Clang lacks that feature, though.
*
* @see https://bugs.llvm.org/show_bug.cgi?id=4898
* @see https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
*/
#include "ruby/3/has/builtin.h"
#if defined(RUBY3_CONSTANT_P)
# /* Take that. */
#elif RUBY3_HAS_BUILTIN(__builtin_constant_p)
# define RUBY3_CONSTANT_P(expr) __builtin_constant_p(expr)
#else
# define RUBY3_CONSTANT_P(expr) 0
#endif